Various carboxylate compounds are known in the art for use in inhibiting the corrosion of metal surfaces. For example, carboxylate compounds have been used alone or in combination with other compounds to prevent corrosion of metals in many fields including industrial cooling systems, engine coolants, hydraulic fluids, metalworking fluids and various other applications. Generally, carboxylate compounds are most effective for inhibiting metal corrosion when used in aqueous solutions. Corrosion inhibiting effects result from the binding of the carboxylate anion to the metal or metal oxide surface.
More specifically, monocarboxylates having an alkyl chain have been used for inhibiting corrosion of metals, for example, ferrous metals in aqueous environments. Generally, the longer the alkyl chain included in the monocarboxylate, the greater the corrosion inhibiting effects provided by the monocarboxylate compound. This has a practical limit, however, owing to the solubility of the alkyl group. Monocarboxylates with alkyl chains of greater than 10 to 12 carbon atoms have progressively less water solubility whereby their corrosion inhibiting effects are reduced and their use in many applications is limited. Dicarboxylate compounds have also been used as corrosion inhibitors and generally have been found to be more efficient at reducing corrosion on metal surfaces as compared with monocarboxylate compounds. It is believed that the increased efficiency in corrosion inhibiting effects is attributable to the two functional groups which are available per alkyl group for binding with the metal or metal oxide surface. The effectiveness of dicarboxylate compounds as corrosion inhibitors is increased with increasing alkyl chain length up to about 10 carbon atoms. When the alkyl chain length is greater than about 10 carbon atoms, the molecules begin to function in a manner similar to two monocarboxylates rather than as a dicarboxylate compound.
There is a continuing demand in various industrial fields for compounds and compositions which will inhibit the corrosion of metal surfaces. Additionally, there is a continuing demand for corrosion inhibiting compounds and compositions which provide improved corrosion inhibiting effects as compared with presently used compounds and compositions.